1. Field of the Invention
The invention relates to the transport of a load, for example an ink-receiver in an inkjet printer, with a conveyor belt system with high accurate successive distance movements to have the availability to manipulate or check the load on accurate positions between or during the successive distance movements.
2. Description of the Related Art
A state-of-the art step conveyor system as shown in FIG. 1, also called a step conveyor or stepper conveyor, is a piece of mechanical handling equipment that carries a load (4) by moving from a start location (40) to an end location (41) in successive distance movements also called discrete step increments. The direction movement from the start location (40) to the end location (41) is called the conveying direction (5). A step conveyor system is a conveyor system that allows quick and efficient transportation for a wide variety of materials such as a load (4). A step conveyor system may be used in many industries, including the automotive, agricultural, computer, electronic, food processing, aerospace, pharmaceutical, chemical, bottling and canning, print finishing, packaging and print industry.
If the step conveyor system, as shown in FIG. 1, comprises two or a plurality of pulleys (2) and a conveyor belt (1)—that rotates around them, it is called a belt conveyor system.
It is known in the state-of-the-art that one of the pulleys in a belt conveyor system is driven by an electric stepper motor to producing a torque to the pulley so by friction of the conveyor belt on the powered pulley the conveyor belt and the load is moved in a conveying direction. This is called a belt step conveyor system. A stepper motor is most commonly used for position control. The use of an electric stepper motor makes the transport of a load more controllable e.g. to change the speed of conveying and move the load on the conveyor belt in successive distance movements.
An example of the belt step conveyor belt system with an electric stepper motor is described for the media transport of a wide-format printer in EP 1235690 A (ENCAD INC)
To correct the flatness, resilience, oblique movement correction and/or the tension of the conveyor belt (1) several solutions are used in general belt conveyor systems which can also be used in a belt step conveyor system. An example is to make the pulleys slightly convex in order to keep the conveyor belt (1) centred. Another example of a general belt conveyor system comprising oblique movement correction mean by controlling an extra pulley is disclosed in U.S. Pat. No. 7,823,720 B (SEIKO EPSON CORP.).
However, still the slip occurring on the powered pulley (3) and the conveyor belt (1) remains difficult to control. This causes incorrect or less accurate positioning of a load on a conveyor belt.
There is still a need to provide a belt step conveyor system having a very exact positioning capability for handling different types and sizes of receiving loads.
US2007/0267274 (WERNER KAMMANN MASCHINENFABRIK) discloses a belt step conveyor system which doesn't guarantee a high accuracy of step increments.